Residential solar electric power pioneer John Schaeffer provides a some quick information about how solar electric power works. John explains how photovoltaic (PV) cells create electricity from sunlight, and why this technology is one of our best bets for a sustainable future in which renewable energy sources replace fossil fuels as a primary way to produce electricity.
Switching to Solar Electric Power. How you can go solar.
Adding solar panels to a home can be expensive or it can be on par with your cost of energy today if you rent your solar electric system. There are a lot of cost effective ways to make your home greener and more energy efficient. Some of the resources provided on Solargies.com offer up eco-friendly ideas.
In this article about how solar electric cells work, we will explain solar cells in order to better understand how they convert the sun's energy into an electrical current. You will learn how we are achieving better results and more effective solar cells. We are improving how we can use the sun's energy on a daily basis. But, we still have more work to do before we will have solar electric systems on the majority of U.S. houses. The solar revolution is coming.
Before our current manufacturing process, our silicon was all electrically neutral. The extra electrons were balanced out by the extra protons in the phosphorous. The missing electrons (holes) were balanced out by the missing protons in the boron. When the holes and electrons mix at the junction between N-type and P-type silicon, however, that neutrality is disrupted. Do all the free electrons fill all the free holes? No. If they did, then the whole arrangement wouldn't be very useful. Right at the junction, however, they do mix and form a barrier, making it harder and harder for electrons on the N side to cross to the P side. Eventually, equilibrium is reached, and we have an electric field separating the two sides. Watch animated explaination of "How the Solar Electric Cell Works"
The effect of the electric field in a PV cell
This electric field acts as a diode, allowing (and even pushing) electrons to flow from the P side to the N side of the silicon wafer. This does not work the other way around. It's like a hill -- electrons can easily go down the hill (to the N side), but can't climb it (to the P side). We have an electric field acting as a diode in which electrons can only move in one direction. When light, in the form of photons, hits the solar electric cell, its energy frees electron-hole pairs.
Each photon with enough energy will normally free exactly one electron. This results in a free hole as well. If this happens close enough to the electric field, or if free electron and free hole happen to wander into its range of influence, the field will send the electron to the N side and the hole to the P side. This causes further disruption of electrical neutrality. If we provide an external current path, the electrons will flow through the path to their original side (the P side) to unite with holes that the electric field sent there. All of this does work for us along the way in the form of electricity . The electron flow provides the current, and the cell's electric field causes a voltage. With both current and voltage, we have power
Operation of a Solar (PV) cell
There are a few more steps left at the molecular level before we can really say our solar cells are producing electricity. Silicon happens to be a very shiny material. This means that it is very reflective. Photons that are reflected can't be used by the cell. For that reason, an antireflective coating is applied to the top of the cell to reduce reflection losses to less than 5 percent. In essense, the surface of the solar electric cell is made sticky so that photons are absorbed versus having them bounce away.
The final step is the glass cover plate that protects the solar cell from the weather, the elements, or your kids baseball. PV modules are made by connecting several solar cells in series and parallel to achieve useful levels of voltage and current. The cells are put into a sturdy frame complete with a glass cover with positive and negative terminals on the back.
Basic structure of a silicon photovoltaic (PV) cell
How much sunlight energy does solar cell absorb? Unfortunately, the most that the current cells can absorb is around 25 percent or maybe even less. Why so little? That is the burning question along with reducing the cost of photovoltaic (PV) cell manufacturing that industry leaders will be working on in the next year or two. Solar electric services and products have evolved a long way. They will continue to evolve for those who wish to purchase systems as well as for those who wish to rent a system and let others take care of the day to day details.
